González Rodríguez, NereaVázquez Liz, NataliaRodríguez Sampedro, AnaRegal López, PatriciaFente Sampayo, Cristina AsunciónLamas Freire, Alexandre2025-10-282025-10-282025-06-272076-3417https://hdl.handle.net/10347/43442The digestion of A1 β-casein present in conventional milk releases β-casomorphin-7 (βCM-7), a bioactive peptide with potential implications for gastrointestinal and neurological health. A scoping review was performed to respond to the following research question: What are the health effects of consuming milk containing the A1 β-casein variant compared to the exclusive consumption of the A2 variant in humans? The evidence collected in this review of human studies with different populations (i.e., children, middle-aged adults, athletes) suggests that the consumption of milk containing A1 β-casein may negatively influence gut health by altering microbial composition, reducing intestinal motility, and increasing colonic fermentation, leading to elevated gas production and altered short-chain fatty acid (SCFA) profiles. The release of βCM-7 upon digestion can also compromise intestinal-barrier integrity, which may exacerbate symptoms of lactose intolerance, irritable bowel syndrome (IBS), or other allergy-related sensitivities. Its ability to cross the blood–brain barrier raises concerns about potential neurological effects. In contrast, milk containing exclusively A2 β-casein is associated with improved gastrointestinal outcomes, including the enhanced abundance of beneficial bacteria such as Bifidobacterium spp. and reduced inflammatory markers.eng© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).http://creativecommons.org/licenses/by/4.0/β-caseinA2 milkHealthImmune functionHuman studiesChildrenMiddleaged adultsAthletesScoping review3206 Ciencias de la nutriciónjournal article10.3390/app151372782076-3417open access